No "obstacle" option in fluid type
That would be the new updates in Blender 2.82 involving mantaflow etc.

I'd suggest that you go look for Mantaflow tutorials such as this one by CG Geek:

However, here's a quick summary of the four options that you have in 2.82:

None - Nothing.

Domain - The area that the fluid simulation stays within. None of the smoke/liquid will ever leave this area.

Flow - This is the actual smoke/liquid/fire emitter. You can change the type and additional settings within the settings of the Flow type.

Effector - These are your obstacles to the liquid simulation.